This application generally relates to automated methods and equipment for laying up plies of composite material, and deals more particularly with a method and apparatus for placing short courses of composite tape on a substrate during the layup process.
Composite structures such as those used in the automotive, marine and aerospace industries may be fabricated using automated composite material application machines, commonly referred to as automated fiber placement (AFP) machines. AFP machines may be used in the aircraft industry, for example, to fabricate structural components and skins by placing relatively narrow strips of composite, slit fiber tape or “tows” on a manufacturing tool. The tape may be placed on the tool in parallel courses that may be in substantially edge-to-edge contact to form a ply.
Known AFP machines employ a tape placement head that dispenses, cuts and compacts courses of tape onto the tool surface as a tape placement head is moved by a robotic device over the tool surface. These tape placement heads typically include a supply spool of tape, and a dispensing mechanism that draws the tape from the spool and guides the tape into a nip between a compaction roller and the tool surface. A cutter blade within the dispensing mechanism located upstream from the compaction roller cuts the tape to a desired course length. The minimum length of a tape course that can be placed by the tape placement head may therefore be governed by the distance between the point where the tape is compacted onto the tool surface and the point where the tape is cut by the blade.
In some applications, relatively short courses may be required which have a length less than the minimum course length that can be cut by known tape heads. In other words, a desired course length may be less than the distance from the compaction point to the point where the cut is made. Under these circumstances, it may be necessary to place courses that are longer than optimum course lengths, thereby adding weight and/or cost to the part, or prompting the need to trim the plies of excess tape, or to manually lay the short courses by hand, thereby adding undesired labor and expense to the manufacturing process.